DP Chemistry (last assessment 2024)

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Question 19M.3.sl.TZ2.c(ii)

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.3.sl.TZ2.c(ii)
Level sl Paper 3 Time zone TZ2
Command term Calculate Question number c(ii) Adapted from N/A
c(ii).
[Maximum mark: 2]
19M.3.sl.TZ2.c(ii)

This question is about a mug made of a lead alloy.

The rate of lead dissolving in common beverages with various pH values was analysed.

A mean daily lead intake of greater than 5.0 × 10−6 g per kg of body weight results in increased lead levels in the body.

Calculate the volume, in dm3, of tap water from experiment 8 which would exceed this daily lead intake for an 80.0 kg man.

[2]

Markscheme

«daily limit = 5.0 × 10–6 g kg–1 × 80.0kg =» 4.0 × 10–4 «g of lead»  [✔]

«volume  4.0 × 10 − 4  g 1.5 × 10 − 2  g d m − 3 =» 2.7 × 10–2/0.027 «dm3»  [✔]

 

Note: Award [2] for correct final answer.

Examiners report

Most students receive one mark for this question, and many receive both marks. The most common mistakes involved incorrect conversions from gram to milligrams or milligrams to grams.

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